Electrical indicating or recording apparatus.



r w'. H1 BRISTOL. ELBOTRIGALINDIGATING 0B RECORDING APPARATUS.`

AryLloATIon 11Ln11 11.12.31:,1912. A 4' Patented Apr. `15, 1913.:

UNTTED sTATEs PATENT onirica WILLIAM H. BRISTOL, OF WATERBURY, CONNECTICUT, ASSIGNOR TO THE BRISTOL COMPANY, OF.WATERBURY CONNECTICUT', A CORPORATION `OF CONNECTICUT.

ELECTRICAL INDICATING 0R RECORDING APPARATUS.

Specification of Letters Patent.

Application filed March 30, 1912.

Patented Apr. 15, 1913.

serial No., 687,450.

T0 all lwhom it may concern:

Be it known that I, WILLIAMH. BRISTOL, a citizen of the United States, and a. resident of Waterbury, in the county of New Haven and State of Connecticut, have invented ce1"- tain new and useful Improvements in Electrical Indicating or Recording Apparatus, of which the following is aA specification.

The invention relates to electrical indicating and recording apparatus, `more particularly to galvanonieters, voltmeters, ammeters or wattmeters for indicatin or recording the strength and pressure o an electric current or the work done thereby. The apparatus is of the type in which' there is a Xed and a movable member, the latter being adapted to be attracted to or repelled from the former; and the invention has for its object to preserve theA accuracy of the apparat-us by providing for the movable member a proper mounting.` This mounting is so constructed and .arranged as to be` lheat generated in the coils, nor subjected to eddy currents.

The nature of :the invention will best be understood when described `in connection with the accompanying` drawings, in which4 Figure 1 is an elevation of the actuating mechanism of a voltmeter to which the invention has been applied,the casing of said voltmeter being shown in section and a portion of the apparatus removed. Fig. 2 is a similar side. view of the actuating lnechanism. Fig. 3 is a detail perspective of a knife-blade mounting and attached indicating or recording arm.

Similar characters of reference designate corresponding parts throughout the several views.

Referringto the drawin s, 10 designates l. suitable casing to whic the actuating mechanism is secured, and is provided with this mutual attraction. The movable coil 15 is supported by a suitable framing 16, which is shown as extending entirely about both coils, although one-half of the same might be omitted. This frame 16 is attached to the movable coil and is carried at its movable coil end` by a flexible spring piece 17. The other end of the frame engages a knife blade 18 mounted `in suitable knife edge bearings 19 of a frame piece 20, and which knife blade is adapted to rock in accordance `with the movement of coil 15 toward and away from the fixed coil l1. The indicating or recording arm 13 is suitably connected with this knife blade 18, partaking of the motion thereof and which corresponde to the movement of coil 15, the latter being` a function of the electric pressure applied to the binding osts 11 and 12. Of course, the coil 15 mig 1t be replaced by a magnetic disk which could be attracted by the' stationa coil 14. In thus providing a supporting rame for the movable coil`15 about said coils 14 and 15, and transmitting the movement of the latter coil therethrough to the indicating or recording arm 13, instead of through a rod extending centrally through the coils as has been the practice heretofore, expansions and contractions of roduced inv the said coil, as well plying device of the character set forth and which is extremely sensitive and susceptible to very small changes in the relative position of the coils, that is to say the movement of one coil toward and away from another. It has been proposed to employ for this purpose a central rod of insulating material which, of course, would provide against the production of heat through eddy currents; but `such rods have not proved satisfactory because of the impossibility of obtainin the material with a practically zero coe cient of expansion, as well as from` the fact that the rods warp considerably. In locating the frame, as herein set forth, beyond the influence of the heat generated in the coils, as well as beyond the range of magnetic influence, none of the difficulties aforesaid are encountered and the instruis movable, of a frame supporting said 1noV` able coil and passing` about said stationary solenoid, a suitable support for one end of said frame, a rocking support for the other end of said frame, and an arm connected with4 said rocking support.

3.` nan electrical measuring instrument, the combination with a stationary member and a movable member within the influence of said stationary member, of a frame supportingf said movable member and passing about said stationary member, a rod extending' from one end of said frame, means to support said rod, a rod extending from the other end of said frame, a rocking support for the said latter rod, and an arm Connected with said rocking; support.

4. In an electricalmeasuring instrument, the combination with a stationary member and a movable member within the inuen'ce of said stationary member, of a frame sup- 4 portmg said movable member and passing v about said stationary member, a rod extending outwardly in the axis of said members from one end of said frame, flexible means to support said rod, a rod extending' in-`l wardly in the axis of said members from the other end of said frame, ar rocking, support for the said latter rod, and an armconnected with said rocking' support.

5. In an electrical measuring' instrument, the combination with two coils, one of whichv ismovable, of a frame supporting-said movablecoil and surrounding both of said coilsgf a rod extendingA outwardly in the axis of said'coils from-one end of said frame, nexible means to support the samea rod extend.

ing,r inwardly in the axis of said coils `from the other end of said frame, a rocking, support .for said latterrod, and an arm connected with saidrockingsupport.

Signed at New York, in the county of New York, and State of New York, this 28th day of March A. 111912.`

WLLAM H. BRISTOL. Witnesses:

FREDK. ESCHUETZ, ,1 LAURA E. SMITH. 

